Hydraulic Binders In A Nutshell: The Basics Of Concrete Solutions

Hydraulic lime is a moderate calcination product of marly limestone containing from 6 to 20% of clay impurities. Normal calcination temperature ranges from 900 to 1,100°C, depending on the feed composition. The product is comprised not only of free lime, but also from chemical compounds with oxides of clay: silicate 2CaO • Si02, aluminates 2CaO • AOz, ferrites 2CaO • BegOz calcium. Like the air lime this product represents lump hydraulic lime, which is subjected to grinding mills to produce fine ground quicklime. Yet there is another production option: lump is slaked and unslaked particles (silicates, aluminates and ferrites) are subjected to further grinding followed by mixing and slaking the unslaked parts.

When interacting with water silicates and aluminates remain virtually non-hydrated. Only when this extinction of lime in the dough gradually formed silicate and calcium hydro-aluminates, accompanied by swelling of the compounds and their transition into the jelly state. Depending on the content of calcium oxide in the lime with respect to the amount of silica, sesqui oxides of aluminum and iron can be divided into strongly-hydraulic and weakly-hydraulic.

Currently, the use of hydraulic lime is quite limited – for mortars and concretes of low strength, for laying in damp areas (basements, canals) in low-rise buildings, and others. It is not manufactured now the novel cement – hydraulic binder, gets crushed into a fine moderately burnt powder (not before sintering) lime or magnesia in the marl clay content in these impurities to 25-35%. This kind of cement is completely replaced by more advanced portland cements.

A true to the type portland cement product represents fine grinding of clinker, the resulting uniform roasting before sintering of natural raw materials (marl) or artificial homogeneous raw material mixture defined by composition containing limestone and clay. In the process of grinding the clinker gypsum added in an amount up to 3.5% (based on sulfuric anhydrite). It is possible to partially replace the feed mixture with blast furnace slag or nepheline sludge, if the necessary raw material retains the calculated composition.

The natural minerals in the form of lime marl are rare, so massive construction and design experts, like a UK-based Telling Company, massively utilising hydraulic lime and lime mortar solutions, oftentimes have to rely mainly on synthetic raw mixtures. As noted, they are compiled with the help of rocks with a high content of calcium carbonate (limestone net, chalk, lime tuff, marl limestone, etc.) and species belonging to the aluminous feedstock (heavy clay, marl clay, shale, etc.). Based on the chemical composition of the raw mixture and the desired characteristics calculated clinker composition ratio between its components with the greatest possible precision. Type of raw materials is reflected in the choice of equipment necessary for its preparation, roasting and grinding calcine with additives and its processing to the state the smallest homogeneous powder – portland cement.



Lifting Equipment: Specs & Feasibility

In general, a protozoan lifting system stands for mechanism of designed for cyclic operation and used for lifting and moving cargo over short distances within a certain area. Lifting machines vary greatly according to the principles of action, purpose, performance, configuration serviced area and etc..

The most common type is the general purpose machines: with universal constructions, they are designed to perform only lifting and transport operations. In particular, such mechanism typically features a self-propelled crawler and mobile crane for general use. Perhaps, the main advantage over other types of cranes lies in its high mobility: ability to quickly move the lifting device from one place to another, install the lifting platform on almost any soil foundation without significant training; compactness usually complements the list of benefits. The obvious advantages look not that brilliant – limited load capacity and too compact dimensions.

Self-propelled cranes with a special truck-mounted chassis is designed for construction, installation, handling, emergency – rehabilitation works on the dispersed objects.

Typically such machines’ hooks are mounted on the telescopic shaft length of 10.6 m to 36.7 m; auxiliary hook can be used as an extension (9.5m or 16m). The crane functioning with the load characteristics is allowed only with the use of the outriggers.

Truck-based lifting machine can be packed with a tower-shaft mechanism and can operate under a certain load or without it, without requiring special balancing mechanisms as stability is provided by gravity. Truck crane is the most common type of mobile jib cranes. The truck cranes are built basing on the mass-produced chassis of trucks with the installation of the frame front and rear outriggers for stability during operating. Their weak points are poor ability to move across offroads and gradeability of up to 25° only.

The strongest suit of mobile cranes is their high mobility, which allows them moving quickly to remote objects. When transporting by rail re-mounting is not required, since they fit into the size of rail transport.

Here are the main types of truck cranes:

  • Trucks with telescopic boom and rigid suspension.
  • Trucks with stack boom with flexible suspension.
  • Tower-boom trucks.
  • Trucks with booms featuring jib.

The systems may be upgraded with extension sections (inserts) or drawers with telescopic lengthened booms and jib booms. Modern lifting devices are taken advantage of in construction and installation sites, in handling, energy construction, they are mainly used for loading and unloading, and as auxiliary crane for assembly operations at zero and minus marks.

The economical feasibility is among the first factors having a direct impact on making the choice in favour of this equipment. Thus, Granada Material Handling, a top UK league industry representative, specialized in lifting equipment inspection and lifting equipment services, claims an average system used on railway junctions pays for itself within the first to years of exploitation. Giving the pace of logistics development, lifting equipment usage gains momentum steadily and consistently, providing companies like GMBH with an opportunity to look beyond domestic market.